Power factor correction (PFC) circuits are used to control the relative phase relationship between voltage and current of a load to an AC supply. PFC circuits may include an initial DC-DC switching converter referred to as a PFC pre-converter that receives a rectified line voltage and generates a DC output voltage while also providing power factor correction. A subsequent DC-DC converter may be included to provide a regulated DC voltage to a load circuit. The PFC DC-DC can be operated by pulse width modulated control signals in a critical conduction mode (CRM or CrCM, also referred to as transition mode (TM)), or in a discontinuous conduction mode (DCM). CRM operation suffers from high switching loss and increased operating frequency at light loading conditions. To improve light loading efficiency, control can be shifted to DCM operation at light loads, while maintaining power factor control. Measuring the peak current of a boost converter inductor to trigger transition from CRM to DCM requires an added sense resistor and an extra integrated circuit pin, which is expensive and increases power loss. Separate interleaved CRM boost converters can be used for higher power applications, but interleaved operation of two converters using DCM control for light loads increases cost and complexity with respect to phase synching and can lead to degraded EMI performance and increased audible noise.